This invention relates to solar energy collectors for converting solar energy to thermal energy, and more particularly, to solar collectors in which a black fluid is used as the absorber and as the heat carrier.
Solar energy collectors for converting solar energy to thermal energy are well known in the art and many various different types of such collectors are disclosed in the prior art. Generally, such absorbers utilize thin black surfaces coated on a heat conducting metallic substrate such as copper, aluminum or steel. The thin surface coating which is absorbing in the wavelength of the solar spectrum converts the solar energy to thermal energy which is transferred into and through the metallic substrate into a flowing fluid, usually water or a mixture of water and an anti-freeze. This flowing fluid provides the necessary temperature differential gradient and is used to transport the thermal energy to the point of use.
Recently, solar collectors have been introduced which provide an improvement over the above described prior art devices by replacing the thin absorbing coatings and metallic substrate with a heat absorbing black fluid which functions as both the absorber and the medium for transporting the thermal energy to the point of use. It will be appreciated that the substitution of a black fluid in solar collectors of conventional design may be advantageous and that solar collectors especially designed for black fluid use may afford optimum advantage.